1. Field of the Invention
The present invention relates to a lens that distributes light so that the light extends into a certain range, and the light distribution is comparatively uniform in that range.
2. Discussion of the Background
A liquid crystal display (LCD) device displays images using optical characteristics (i.e. refractive anisotropy) and electrical characteristics (i.e. dielectric anisotropy) of liquid crystal. The LCD device has advantageous characteristics such as thinner thickness, lower driving voltage, lower power consumption, etc., than other types of display devices such as a cathode ray tube (CRT) device, a plasma display panel (PDP) device, and the like.
The LCD device is non-emissive type display device, which requires a light source to supply light to a liquid crystal (LC) panel of the LCD device.
The backlight assembly is classified either as an edge illumination type or a direct illumination type based on the location of the light source.
In the edge illumination type, the backlight assembly includes a light guiding plate and one or two light sources adjacent to a side surface of the light guiding plate so that the light generated from the light sources is guided into the LC panel of the LCD device.
In the direct illumination type, the backlight assembly includes a plurality of light sources under the LC panel and a diffusion plate disposed between the LCD panel and the light sources so that the light generated from the light sources is diffused and irradiated into the LC panel.
In general, a small screen LCD device has the edge illumination type backlight assembly with thin thickness and a large screen LCD device has the direct illumination type backlight assembly with high luminance.
When the LCD device has the direct illumination type backlight assembly, it is important that the backlight assembly should provide uniform brightness through the whole area of the backlight assembly.